I've just had the same problem. One of my 4 year olds never came up, while all 6 have been up for almost a week. I have a hibernation cave, and couldn't imagine how she could have gotten out. I just went in there, on my knees and dug around in the cave, and she was buried all the way in the back....still sleeping. I'm thinking it was cooler in the back of the cave where the sun didn't hit. I would only suggest getting down on your knees and crawling all around and digging with your hands.